Demo_01 is the fourth extended play from South Korean boy band Pentagon.

Demo_01 was first announced on August 25, 2017 with a release date of September 6.

[1] Beginning on August 29, various teasers were unveiled in order to promote the mini-album.

[2] A set of teaser photos of each member, as well as a group shot, were published.

[4] By the end of the month, the record shifted 13,759 units domestically.